usertools: fix device binding module detection

usertools: fix device binding module detection

Some kernel modules use '-' in their name when registering through
`pci_register_driver` and the same name  is populated in
'/sys/bus/pci/drivers/'.
But the kernel always populates modules names replacing '-' with '_'
in '/sys/module/'.

Example:
	# ./usertools/dpdk-devbind.py -b octeontx2-nicpf 0002:03:00.0
	Error: Driver 'octeontx2-nicpf' is not loaded.

	# ls /sys/bus/pci/drivers/octeontx2-nicpf
	bind  module  new_id  remove_id  uevent  unbind
	# ls /sys/module/octeontx2_nicpf/
	drivers  uevent  version

The patch addresses it by always replacing '-' with '_' when looking in
'/sys/module/'

Signed-off-by: Phanendra Vukkisala <pvukkisala@marvell.com>
Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>